Spatio-temporal data comparisons for global highly pathogenic avian influenza (HPAI) H5N1 outbreaks

Highly pathogenic avian influenza subtype H5N1 is a zoonotic disease and control of the disease is one of the highest priority in global health. Disease surveillance systems are valuable data sources for various researches and management projects, but the data quality has not been paid much attention in previous studies. Based on data from two commonly used databases (Office International des Epizooties (OIE) and Food and Agriculture Organization of the United Nations (FAO)) of global HPAI H5N1 outbreaks during the period of 2003-2009, we examined and compared their patterns of temporal, spatial and spatio-temporal distributions for the first time. OIE and FAO data showed similar trends in temporal and spatial distributions if they were considered separately. However, more advanced approaches detected a significant difference in joint spatio-temporal distribution. Because of incompleteness for both OIE and FAO data, an integrated dataset would provide a more complete picture of global HPAI H5N1 outbreaks. We also displayed a mismatching profile of global HPAI H5N1 outbreaks and found that the degree of mismatching was related to the epidemic severity. The ideas and approaches used here to assess spatio-temporal data on the same disease from different sources are useful for other similar studies.     

Indications that live poultry markets are a major source of human H5N1 influenza virus infection in China

Human infections of H5N1 highly pathogenic avian influenza virus have continued to occur in China without corresponding outbreaks in poultry, and there is little conclusive evidence of the source of these infections. Seeking to identify the source of the human infections, we sequenced 31 H5N1 viruses isolated from humans in China (2005 to 2010). We found a number of viral genotypes, not all of which have similar known avian virus counterparts. Guided by patient questionnaire data, we also obtained environmental samples from live poultry markets and dwellings frequented by six individuals prior to disease onset (2008 and 2009). H5N1 viruses were isolated from 4 of the 6 live poultry markets sampled. In each case, the genetic sequences of the environmental and corresponding human isolates were highly similar, demonstrating a link between human infection and live poultry markets. Therefore, infection control measures in live poultry markets are likely to reduce human H5N1 infection in China.     

Possible circulation of H5N1 avian influenza viruses in healthy ducks on farms in northern Vietnam

To estimate the prevalence of influenza A subtype H5N1 viruses among domestic ducks in the period between October and November 2006 when H5N1 outbreaks had been absent, 1106 healthy ducks raised in northern Vietnam were collected. Inoculation of all throat and cloacae samples into embryonated eggs resulted in the isolation of subtype H3N8 in 13 ducks, but not H5N1 viruses. Serological analyses demonstrated that five ducks (0.45%) solely developed H5N1 subtype-specific hemagglutinin-inhibiting and neuraminidase-inhibiting antibodies together with anti-non-structural protein 1 antibodies. The results suggested that the ducks were naturally infected with H5N1 viruses when obvious H5N1 outbreaks were absent.     

Isolation and characterization of avian influenza viruses, including highly pathogenic H5N1, from poultry in live bird markets in Hanoi, Vietnam, in 2001

Since 1997, outbreaks of highly pathogenic (HP) H5N1 and circulation of H9N2 viruses among domestic poultry in Asia have posed a threat to public health. To better understand the extent of transmission of avian influenza viruses (AIV) to humans in Asia, we conducted a cross-sectional virologic study in live bird markets (LBM) in Hanoi, Vietnam, in October 2001. Specimens from 189 birds and 18 environmental samples were collected at 10 LBM. Four influenza A viruses of the H4N6 (n = 1), H5N2 (n = 1), and H9N3 (n = 2) subtypes were isolated from healthy ducks for an isolation frequency of over 30% from this species. Two H5N1 viruses were isolated from healthy geese. The hemagglutinin (HA) genes of these H5N1 viruses possessed multiple basic amino acid motifs at the cleavage site, were HP for experimentally infected chickens, and were thus characterized as HP AIV. These HA genes shared high amino acid identities with genes of other H5N1 viruses isolated in Asia during this period, but they were genetically distinct from those of H5N1 viruses isolated from poultry and humans in Vietnam during the early 2004 outbreaks. These viruses were not highly virulent for experimentally infected ducks, mice, or ferrets. These results establish that HP H5N1 viruses with properties similar to viruses isolated in Hong Kong and mainland China circulated in Vietnam as early as 2001, suggest a common source for H5N1 viruses circulating in these Asian countries, and provide a framework to better understand the recent widespread emergence of HP H5N1 viruses in Asia.     

Evolution of highly pathogenic H5N1 avian influenza viruses in Vietnam between 2001 and 2007

Highly pathogenic avian influenza (HPAI) H5N1 viruses have caused dramatic economic losses to the poultry industry of Vietnam and continue to pose a serious threat to public health. As of June 2008, Vietnam had reported nearly one third of worldwide laboratory confirmed human H5N1 infections. To better understand the emergence, spread and evolution of H5N1 in Vietnam we studied over 300 H5N1 avian influenza viruses isolated from Vietnam since their first detection in 2001. Our phylogenetic analyses indicated that six genetically distinct H5N1 viruses were introduced into Vietnam during the past seven years. The H5N1 lineage that evolved following the introduction in 2003 of the A/duck/Hong Kong/821/2002-like viruses, with clade 1 hemagglutinin (HA), continued to predominate in southern Vietnam as of May 2007. A virus with a clade 2.3.4 HA newly introduced into northern Vietnam in 2007, reassorted with pre-existing clade 1 viruses, resulting in the emergence of novel genotypes with neuraminidase (NA) and/or internal gene segments from clade 1 viruses. A total of nine distinct genotypes have been present in Vietnam since 2001, including five that were circulating in 2007. At least four of these genotypes appear to have originated in Vietnam and represent novel H5N1 viruses not reported elsewhere. Geographic and temporal analyses of H5N1 infection dynamics in poultry suggest that the majority of viruses containing new genes were first detected in northern Vietnam and subsequently spread to southern Vietnam after reassorting with pre-existing local viruses in northern Vietnam. Although the routes of entry and spread of H5N1 in Vietnam remain speculative, enhanced poultry import controls and virologic surveillance efforts may help curb the entry and spread of new HPAI viral genes.     

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam

Background

Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.

Methods and Findings

Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.

Conclusion

In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.     

Surveillance and isolation of HPAI H5N1 from wild Mandarin Ducks (Aix galericulata)

Highly pathogenic avian influenza (HPAI) H5N1 virus circulates among a variety of free-ranging wild birds and continually poses a threat to animal and human health. During the winter of 2010-2011, we surveyed Korean wild bird habitats. From 728 fresh fecal samples, 14 HPAI H5N1 viruses were identified. The isolates phylogenetically clustered with other recently isolated clade 2.3.2 HPAI H5N1 viruses isolated from wild birds in Mongolia. All HPAI-positive fecal samples were analyzed by DNA barcoding for host-species identification. Twelve of the 14 HPAI-positive samples were typed as Mandarin Duck (Aix galericulata). The high incidence of HPAI subtype H5N1 viruses in wild Mandarin Duck droppings is a novel finding and underscores the need for enhanced avian influenza virus surveillance in wild Mandarin Ducks. Further investigation of the susceptibility of Mandarin Ducks to HPAI H5N1 clade 2.3.2 virus would aid the understanding of HPAI ecology and epidemiology in wild birds.     

Control of a highly pathogenic H5N1 avian influenza outbreak in the GB poultry flock

The identification of H5N1 in domestic poultry in Europe has increased the risk of infection reaching most industrialized poultry populations. Here, using detailed data on the poultry population in Great Britain (GB), we show that currently planned interventions based on movement restrictions can be expected to control the majority of outbreaks. The probability that controls fail to keep an outbreak small only rises to significant levels if most transmission occurs via mechanisms which are both untraceable and largely independent of the local density of premises. We show that a predictor of the need to intensify control efforts in GB is whether an outbreak exceeds 20 infected premises. In such a scenario neither localized reactive vaccination nor localized culling are likely to have a substantial impact. The most effective of these contingent interventions are large radius (10 km) localized culling and national vaccination. However, the modest impact of these approaches must be balanced against their substantial inconvenience and cost.     

Temperature drops and the onset of severe avian influenza A H5N1 virus outbreaks

Global influenza surveillance is one of the most effective strategies for containing outbreaks and preparing for a possible pandemic influenza. Since the end of 2003, highly pathogenic avian influenza viruses (HPAI) H5N1 have caused many outbreaks in poultries and wild birds from East Asia and have spread to at least 48 countries. For such a fast and wide-spreading virulent pathogen, prediction based on changes of micro- and macro-environment has rarely been evaluated. In this study, we are developing a new climatic approach by investigating the conditions that occurred before the H5N1 avian influenza outbreaks for early predicting future HPAI outbreaks and preventing pandemic disasters. The results show a temperature drop shortly before these outbreaks in birds in each of the Eurasian regions stricken in 2005 and 2006. Dust storms, like those that struck near China's Lake Qinghai around May 4, 2005, exacerbated the spread of this HPAI H5N1 virus, causing the deaths of a record number of wild birds and triggering the subsequent spread of H5N1. Weather monitoring could play an important role in the early warning of outbreaks of this potentially dangerous virus.     

Ecological determinants of highly pathogenic avian influenza (H5N1) outbreaks in Bangladesh

Background

The agro-ecology and poultry husbandry of the south Asian and south-east Asian countries share common features, however, with noticeable differences. Hence, the ecological determinants associated with risk of highly pathogenic avian influenza (HPAI-H5N1) outbreaks are expected to differ between Bangladesh and e.g., Thailand and Vietnam. The primary aim of the current study was to establish ecological determinants associated with the risk of HPAI-H5N1 outbreaks at subdistrict level in Bangladesh. The secondary aim was to explore the performance of two different statistical modeling approaches for unmeasured spatially correlated variation.

Methodology/Principal Findings

An ecological study at subdistrict level in Bangladesh was performed with 138 subdistricts with HPAI-H5N1 outbreaks during 2007–2008, and 326 subdistricts with no outbreaks. The association between ecological determinants and HPAI-H5N1 outbreaks was examined using a generalized linear mixed model. Spatial clustering of the ecological data was modeled using 1) an intrinsic conditional autoregressive (ICAR) model at subdistrict level considering their first order neighbors, and 2) a multilevel (ML) model with subdistricts nested within districts. Ecological determinants significantly associated with risk of HPAI-H5N1 outbreaks at subdistrict level were migratory birds'' staging areas, river network, household density, literacy rate, poultry density, live bird markets, and highway network. Predictive risk maps were derived based on the resulting models. The resulting models indicate that the ML model absorbed some of the covariate effect of the ICAR model because of the neighbor structure implied in the two different models.

Conclusions/Significance

The study identified a new set of ecological determinants related to river networks, migratory birds'' staging areas and literacy rate in addition to already known risk factors, and clarified that the generalized concept of free grazing duck and duck-rice cultivation interacted ecology are not significant determinants for Bangladesh. These findings will refine current understanding of the HPAI-H5N1 epidemiology in Bangladesh.     

家禽市场污水来源的H5N1亚型禽流感病毒NS基因分析

对长沙市家禽市场污水来源的H5N1亚型禽流感病毒(Avian influenza viruses,AIV)的非结构蛋白(Non-structural,NS)基因进行进化和分子特征分析,探讨污水中H5N1病毒的传播风险。9份家禽市场环境污水H5N1亚型AIV标本进行NS基因TA克隆测序,测序结果利用Lasergene和Mega5软件进行氨基酸(amine acid,aa)比对和进化树分析。共得到8个阳性克隆,进化树构建显示8个H5N1的NS基因均属于A亚群,其编码的NS1和NS2蛋白与A亚群代表株(A/chicken/Hubei/w h/1999)aa同源性分别为90.1%～92.5%和91.0%～92.6%,8个H5N1的NS1和NS2aa之间的同源性分别为93.8%～100.0%和98.4%～100.0%。8个H5N1的NS1蛋白均具有缺失80～84位aa、C末端携带有ESEV的PL基序和第92位aa为E的高致病性分子特征。家禽市场污水来源的H5N1亚型AIV的NS基因具有高致病性的分子特征,这种基因特征表明污水可能传播H5N1病毒。     

H9N2 influenza viruses possessing H5N1-like internal genomes continue to circulate in poultry in southeastern China

The transmission of H9N2 influenza viruses to humans and the realization that the A/Hong Kong/156/97-like (H5N1) (abbreviated HK/156/97) genome complex may be present in H9N2 viruses in southeastern China necessitated a study of the distribution and characterization of H9N2 viruses in poultry in the Hong Kong SAR in 1999. Serological studies indicated that H9N2 influenza viruses had infected a high proportion of chickens and other land-based birds (pigeon, pheasant, quail, guinea fowl, and chukka) from southeastern China. Two lineages of H9N2 influenza viruses present in the live-poultry markets were represented by A/Quail/Hong Kong/G1/97 (Qa/HK/G1/97)-like and A/Duck/Hong Kong/Y280/97 (Dk/HK/Y280/97)-like viruses. Up to 16% of cages of quail in the poultry markets contained Qa/HK/G1/97-like viruses, while about 5% of cages of other land-based birds were infected with Dk/HK/Y280/97-like viruses. No reassortant between the two H9N2 virus lineages was detected despite their cocirculation in the poultry markets. Reassortant viruses represented by A/Chicken/Hong Kong/G9/97 (H9N2) were the major H9N2 influenza viruses circulating in the Hong Kong markets in 1997 but have not been detected since the chicken slaughter in 1997. The Qa/HK/G1/97-like viruses were frequently isolated from quail, while Dk/HK/Y280/97-like viruses were predominately associated with chickens. The Qa/HK/G1/97-like viruses were evolving relatively rapidly, especially in their PB2, HA, NP, and NA genes, suggesting that they are in the process of adapting to a new host. Experimental studies showed that both H9N2 lineages were primarily spread by the aerosol route and that neither quail nor chickens showed evidence of disease. The high prevalence of quail infected with Qa/HK/G1/97-like virus that contains six gene segments genetically highly related to HK/156/97 (H5N1) virus emphasizes the need for surveillance of mammals including humans.     

Lethality to ferrets of H5N1 influenza viruses isolated from humans and poultry in 2004

The 2004 outbreaks of H5N1 influenza viruses in Vietnam and Thailand were highly lethal to humans and to poultry; therefore, newly emerging avian influenza A viruses pose a continued threat, not only to avian species but also to humans. We studied the pathogenicity of four human and nine avian H5N1/04 influenza viruses in ferrets (an excellent model for influenza studies). All four human isolates were fatal to intranasally inoculated ferrets. The human isolate A/Vietnam/1203/04 (H5N1) was the most pathogenic isolate; the severity of disease was associated with a broad tissue tropism and high virus titers in multiple organs, including the brain. High fever, weight loss, anorexia, extreme lethargy, and diarrhea were observed. Two avian H5N1/04 isolates were as pathogenic as the human viruses, causing lethal systemic infections in ferrets. Seven of nine H5N1/04 viruses isolated from avian species caused mild infections, with virus replication restricted to the upper respiratory tract. All chicken isolates were nonlethal to ferrets. A sequence analysis revealed polybasic amino acids in the hemagglutinin connecting peptides of all H5N1/04 viruses, indicating that multiple molecular differences in other genes are important for a high level of virulence. Interestingly, the human A/Vietnam/1203/04 isolate had a lysine substitution at position 627 of PB2 and had one to eight amino acid changes in all gene products except that of the M1 gene, unlike the A/chicken/Vietnam/C58/04 and A/quail/Vietnam/36/04 viruses. Our results indicate that viruses that are lethal to mammals are circulating among birds in Asia and suggest that pathogenicity in ferrets, and perhaps humans, reflects a complex combination of different residues rather than a single amino acid difference.     

Impact of education and network for avian influenza H5N1 in human: knowledge, clinical practice, and motivation on medical providers in Vietnam

Background

Knowledge, clinical practice, and professional motivation of medical providers relating to H5N1 infection have an important influence on care for H5N1 patients who require early diagnosis and early medical intervention.

Methods/Principal Findings

Novel educational programs including training and workshops for medical providers relating to H5N1 infection in Vietnam were originally created and implemented in 18 provincial hospitals in northern Vietnam between 2008 and 2010. A self-administered, structured questionnaire survey was conducted in 8 provincial hospitals where both educational training and workshops were previously provided. A total of 326 medical providers, including physicians, nurses, and laboratory technicians who attended or did not attend original programs were enrolled in the survey. Knowledge, clinical attitudes and practice (KAP), including motivation surrounding caring for H5N1 patients, were evaluated. The study indicated a high level of knowledge and motivation in all professional groups, with especially high levels in laboratory technicians. Conferences and educational programs were evaluated to be the main scientific information resources for physicians, along with information from colleagues. The chest radiographs and the initiation of antiviral treatment in the absence of RT-PCR result were identified as gaps in education. Factors possibly influencing professional motivation for caring for H5N1 patients included healthcare profession, the hospital where the respondents worked, age group, attendance at original educational programs and at educational programs which were conducted by international health-related organizations.

Conclusions

Educational programs provide high knowledge and motivation for medical providers in Vietnam caring for H5N1 patients. Additional educational programs related to chest radiographs and an initiation of treatment in the absence of RT-PCR are needed. Networking is also necessary for sharing updated scientific information and practical experiences. These enhanced KAPs by educational programs and integrated systems among hospitals should result in appropriate care for H5N1 patients and may reduce morbidity and mortality.     

Reassortment between Avian H5N1 and Human H3N2 Influenza Viruses in Ferrets: a Public Health Risk Assessment

This study investigated whether transmissible H5 subtype human-avian reassortant viruses could be generated in vivo. To this end, ferrets were coinfected with recent avian H5N1 (A/Thailand/16/04) and human H3N2 (A/Wyoming/3/03) viruses. Genotype analyses of plaque-purified viruses from nasal secretions of coinfected ferrets revealed that approximately 9% of recovered viruses contained genes from both progenitor viruses. H5 and H3 subtype viruses, including reassortants, were found in airways extending toward and in the upper respiratory tract of ferrets. However, only parental H5N1 genotype viruses were found in lung tissue. Approximately 34% of the recovered reassortant viruses possessed the H5 hemagglutinin (HA) gene, with five unique H5 subtypes recovered. These H5 reassortants were selected for further studies to examine their growth and transmissibility characteristics. Five H5 viruses with representative reassortant genotypes showed reduced titers in nasal secretions of infected ferrets compared to the parental H5N1 virus. No transmission by direct contact between infected and naïve ferrets was observed. These studies indicate that reassortment between H5N1 avian influenza and H3N2 human viruses occurred readily in vivo and furthermore that reassortment between these two viral subtypes is likely to occur in ferret upper airways. Given the relatively high incidence of reassortant viruses from tissues of the ferret upper airway, it is reasonable to conclude that continued exposure of humans and animals to H5N1 alongside seasonal influenza viruses increases the risk of generating H5 subtype reassortant viruses that may be shed from upper airway secretions.Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype have caused devastating outbreaks in avian species during the past decade. After emerging in the Guangdong province of China in 1996, H5N1 viruses have extended their geographic distribution from Asia into Europe and Africa (45, 51). Sporadic transmission of H5N1 viruses from infected birds to humans has resulted in over 380 laboratory-confirmed infections and a case fatality rate of ∼60% since 2003 (48). Currently circulating H5N1 viruses lack the ability to undergo efficient and sustained transmission among humans although instances of limited human-to-human transmission have been reported (13, 41). If H5N1 viruses were to acquire genetic changes that confer efficient transmissibility among humans, then another pandemic would likely occur.The pandemics of 1957 and 1968 highlight the importance of genetic reassortment between avian and human influenza viruses as a mechanism for the generation of human pandemic strains (15, 46, 47). The structural separation of the influenza virus genome into eight independent genes allows formation of hybrid progeny viruses during coinfections. The 1957 H2N2 and 1968 H3N2 pandemic viruses acquired the hemagglutinin (HA) and PB1 genes, with or without the neuraminidase (NA) gene, respectively, from an avian virus progenitor (14, 33). The remaining genes of these pandemic reassortants were derived from a contemporary human virus (14, 33). The host species in which such human pandemic strains were generated by reassortment between human and avian viruses is not known. However, coinfection of the same cell with both human and avian viruses must have occurred, even though human and avian influenza viruses have preferences for different sialic acid receptor structures present on cell surface glycoproteins and glycolipids (20, 30). The HA of human viruses preferentially binds α(2,6)-linked sialic acids while that of avian viruses preferentially bind α(2,3)-linked sialic acids (3, 12). Cells possessing both of these receptors could support coinfection of avian and human viruses, leading to reassortment.Human respiratory tract epithelial cells can possess surface glycans with α(2,3)- and α(2,6)-linked sialic acids and as such represent a potential host for the generation of avian-human reassortant viruses (24, 35). The general distribution of surface α(2,3)- and α(2,6)-linked sialic acids varies among cells of the human upper and lower respiratory tracts, which are anatomically separated by the larynx. Recent studies have shown that α(2,3)-linked sialic acids are present in tissues of the human lower respiratory tract (i.e., lung alveolar cells) (24, 35) as well as tissues of the human upper respiratory tract (24). Consistent with these findings, HPAI H5N1 viruses have been shown to attach to and infect tissues belonging to the lower respiratory tract (i.e., trachea, bronchi, and lung) (5, 25, 35, 40, 42, 43) as well as tissues belonging to the upper respiratory tract (i.e., nasopharyngeal, adenoid, and tonsillar) (25). Glycans with α(2,6)-linked sialic acids are more widespread on epithelial cells of the upper airways than lung alveoli (24, 35). In accordance, human seasonal influenza viruses preferentially attach to and infect cells of the upper respiratory tract (6, 25, 35, 43). If cells with both types of receptors are present in the human respiratory tract, simultaneous infection of a person with both human and avian viruses could generate reassortant viruses.Although viruses derived by reassortment between avian H5N1 and human H3N2 progenitors have been generated in vitro (17), reassortment between these avian and human strains in a coinfected mammalian host has not been shown. Furthermore, our knowledge of the genetic and phenotypic repertoire of such reassortants generated in vivo and their potential for transmission to uninfected hosts is limited (2, 17). In the present study, we used the ferret model to better understand the generation of reassortant viruses in a host coinfected with contemporary avian (H5N1) and human (H3N2) viruses and the extent to which such reassortants replicate and transmit from animal to animal. The domestic ferret (Mustela putoris) serves as an ideal small-animal model for influenza because ferrets are susceptible to human and avian influenza viruses, including HPAI H5N1 viruses, and reflect the relative transmissibility of human and avian influenza viruses in humans (9, 17, 18, 31, 36, 39, 53). Our study revealed that coinfection of ferrets reproducibly generated reassortant viruses that could be recovered from tissues within and extending toward the upper respiratory tract. Although H5 reassortant viruses were recovered from the upper airways, they displayed no transmissibility to contact ferrets, suggesting that additional functional changes are required for these viral subtypes to become pandemic within human populations.     

Changes in Poultry Handling Behavior and Poultry Mortality Reporting among Rural Cambodians in Areas Affected by HPAI/H5N1

Background

Since 2004, 21 highly pathogenic avian influenza H5N1 outbreaks in domestic poultry and eight human cases have been confirmed in Cambodia. As a result, a large number of avian influenza education campaigns have been ongoing in provinces in which H5N1outbreaks have occurred in humans and/or domestic poultry.

Methodology/Principal Findings

Data were collected from 1,252 adults >15 years old living in two southern provinces in Cambodia where H5N1 has been confirmed in domestic poultry and human populations using two cross-sectional surveys conducted in January 2006 and in November/December 2007. Poultry handling behaviors, poultry mortality occurrence and self-reported notification of suspect H5N1 poultry cases to animal health officials in these two surveys were evaluated. Our results demonstrate that although some at risk practices have declined since the first study, risky contact with poultry is still frequent. Improved rates of reporting poultry mortality were observed overall, but reporting to trained village animal health workers decreased by approximately 50%.

Conclusions/Significance

Although some improvements in human behavior have occurred, there are still areas—particularly with respect to the handling of poultry among children and the proper treatment of poultry and the surrounding household environment—that need to be addressed in public health campaigns. Though there were some differences in the sampling methods of the 2006 and 2007 surveys, our results illustrate the potential to induce considerable, potentially very relevant, behavioral changes over a short period of time.     

Avian influenza (H5N1) virus of clade 2.3.2 in domestic poultry in India

South Asia has experienced regular outbreaks of H5N1 avian influenza virus since its first detection in India and Pakistan in February, 2006. Till 2009, the outbreaks in this region were due to clade 2.2 H5N1 virus. In 2010, Nepal reported the first outbreak of clade 2.3.2 virus in South Asia. In February 2011, two outbreaks of H5N1 virus were reported in the State of Tripura in India. The antigenic and genetic analyses of seven H5N1 viruses isolated during these outbreaks were carried out. Antigenic analysis confirmed 64 to 256-fold reduction in cross reactivity compared with clade 2.2 viruses. The intravenous pathogenicity index of the isolates ranged from 2.80-2.95 indicating high pathogenicity to chickens. Sequencing of all the eight gene-segments of seven H5N1 viruses isolated in these outbreaks was carried out. The predicted amino acid sequence analysis revealed high pathogenicity to chickens and susceptibility to the antivirals, amantadine and oseltamivir. Phylogenetic analyses indicated that these viruses belong to clade 2.3.2.1 and were distinct to the clade 2.3.2.1 viruses isolated in Nepal. Identification of new clade 2.3.2 H5N1 viruses in South Asia is reminiscent of the introduction of clade 2.2 viruses in this region in 2006/7. It is now important to monitor whether the clade 2.3.2.1 is replacing clade 2.2 in this region or co-circulating with it. Continued co-circulation of various subclades of the H5N1 virus which are more adapted to land based poultry in a highly populated region such as South Asia increases the risk of evolution of pandemic H5N1 strains.